Substituted thieno uracils and methods of preparing same



Patented Dec. 16, 1947 UNITED STATES PATENT OFFICE SUBSTITUTED THIENOURACILS AND METHODS OF PREPARING SAME No Drawing. Application June 8,1946, Serial No. 675,327

10 Claims. 1 The present invention relates to tetrahydrothieno uracilsand to methods of preparing the same and is a continuation in part of mypending application Serial No. 610,185, filed August 10, 1945.

I have discovered a method of preparing the I ti -substitutedtetrahydrothieno uracils which comprises heating a2-substituted-4-carbamylthiophane-3-isocyanate with a carboxylic acidanhydride and a mild alkali. This method may be illustrated by thefollowing general equation:

in which X is a member of the group consisting of hydrogen, aliphaticand aromatic radicals and R is a non-functional radical such ashydrogen, alkyl, carboxy, carboxyalkyl, carbalkoxyalkyl,carbaryloxyalkyl or other organic radical which does not react with thereagents employed in the reaction.

In general, the compounds of the present invention are white crystallinesolids, slightly soluble in water, methanol, ethanol, dioxane, and otheroxygenated solvents. They are particularly useful as intermediates inthe preparation of compounds having biological activity such as biotinand other compounds having anti-biotin activity.

In preparing the compounds of the present inention, I heat a carbamylthiophane isocyanate ugth an anhydride of a carboxylic acid, prefera 1ya volatile one, such as acetic or propionic anhydride and an alkalinesubstance such as sodium carbonate, sodium bicarbonate, potassiumacetate, sodium acetate and tertiary organic bases such as pyridine,triethylamine, tributylamine, etc. The reaction mixture may be heated ata temperature of from 50 to 150 C. for from 5 minutes to about 5 hours.However, I prefer to carry out the reaction at refluxing temperatureswhich usually takes from 15 minutes to an hour and a half. Although asolvent is usually not necessary, I can, if desired, use a solvent suchas.

dioxane, dibutyl ether, acetic acid, propionic acid, etc.

When carrying out the reaction described above, using an anhydride suchas acetic anhydride, a uracil compound is obtained having an acetylradical attached to the nitrogen directly 2 attached to the thiophanenucleus. While this intermediate can be isolated, I prefer not toisolate it, but to heat the reaction mixture with a mineral acid thusremoving the group. The desired product of the invention is thenrecovered from the reaction mixture by concentrating the mixture, addingwater to precipitate the product, and separating by filtration. Theproduct can be further purified by recrystallization from methylCellosolve, water, methanol, ethanol, propanol or mixtures thereof.

I can use a number of 2-substituted 4-carbamylthiophane-B-isocyanates asintermediates to prepare the compounds of the present invention. Amongthese may be mentioned specifically: 2-(delta-carboxybutyl)-4-carbanilidothiophane 3- isocyanate; 2-(delta-carboxybutyl) -4-carbamylthiophane-3-isocyanate 2-(epsilon-hydroxyamyD-4-carbanilido thiophane-3-isocyanate; 2-propyl-4-carbanilidothiophane-3-isocyanate; 2- (delta carboxybutyl) 4methylcarbamylthiophane-3-isocyanate; 2- (gamma-carboxypropyl)4-carbanilidothiophane-3-isocyanate; 2- (deltaphenoxybutyl) 4carbanilidothiophane 3- isocyanate; 2(gamma-methoxypropyl) 4carbanilidothiophane 3 isocyanate; 2- (delta-carboxybutyl) 4ethylcarbamylthiophane 3 isocyanate; 2- (delta-methoxybutyl)-4-carbanilidothiophane 3 isocyanate; 2 (gamma phenoxypropyl) 4carbanilidothiophane 3 isocyanate; 2 (delta carbomethoxybutyl) 4carbanilidothiophane 3 isocyanate; 2 carboxy-4-carbanilidothiophane-3-isocyanate; and others.

The process of the present invention provides a method of converting3,4-substituted-transthiophanes into the cis configuration. In order toobtain d1 biotin the 3,4-diaminothiophane used in the final step of myprocess should have the cis configuration. I can obtain the desired 3,4-cis-diaminothiophane from the thieno uracils of the present invention bycleaving the uracil ring with hydrazine hydrate to obtain aureylenethiophane cis carboxyhydrazide. These compounds can be made toundergo a simultaneous rearrangement and ring closure giving asubstituted imidazolidothiophane. The imidazolidothiophanes can beconverted to a 3,4-cis-diaminothiophane which is directly convertible todl biotin by treatment with phosgene.

My invention will now be illustrated in greater detail by means of thefollowing specific examples, in which representative thieno uracils areprepared from corresponding carbamylthiophane isocyanates. It will beunderstood, of course, that these examples are given for purposes ofmixture was poured on ice.

4,5-dihydrothiophene-3,4 --dicaiboxylic illustration and are not to beconsidered as limiting my invention to the particular details describedtherein.

Example 1 liquid hydrogen cyanide at C. was added 0.3

cc. of 50% potassium hydroxide. After 16 hours at 0 C., the mixture wasacidified with 1 cc. of 85% phosphoric acid and the volatile materialremoved in vacuo; finally at 100 C. a yield of 63 g. of 2-(delta-carbomethoxybutyl)-3-hydroxy- 3-cyano-4-carbomethoxythiophane wasobtained as a nearly colorless oil which partially crystallized onstanding.

A solution of 62.5 g. of the cyanohydrin prepared immediately above in100 cc. of benzene was dried with anhydrous sodium sulfate and thedrying agent rinsed with 50 cc. of benzene. To the solution diluted with150 cc. of reagent pyridine was added 43 cc. of phosphorus oxy chloride.The temperature gradually rose to 40 C. and occasionally cooled "tomaintain the tem erature at 40 'C.-48 C. After six hours the Theseparated organic layer, washed successively "with dilute hydrochloricacid, aqueous sodium bicarbonate and dilute hydrochloric acid was thendistilled. A yield of 41 g. of 2-(delta-carboniethoxybutyl) '-3- cyano 4carbomethoxy -4,5= dihydrothiophene was obtained as a yellow oil,boiling point 192-198 C. (1 mm).

A-so lution of 29.2 g. of the intermediate above in 90 cc. of aceticacid and 150 cc. of concentrated hydrochloric acid was refluxed forsixteen hours, then evaporated to dryness in vacuo. The residue wasextracted with 300 cc. of hot acetone, filtered from ammonium chlorideand the extract evaporated to dryness in vacuo. 'A quantitative yield of2- (delta -carboxybutyl) =45=dihy-drothiophene- 3,4-di'oarboxylic acidwas obtained as a semicry'stalline mass.

A'solution of 23.5 got 2-(delta carboxybi1tyl) acid in 106 -cc. of 10%sodium hydroxide and 140cc. of water was stirred with 265 g. of 2%sodium The decanted solution was acidified, saturated with sodiumchloride and extracted with two 250 cc. portions of ethyl acetate. Theextracts, dried with anhydrous magnesium sulfate, were evaporatedtodryness and trie-se'mi-crystalline residue (225 g.) recrystallized from124 ethyl 'a'cetatebenzene mixture. A yield of 11.4 g. (49%) 'of2-(delta carboxy-b-utyl) -thiophane-'3,4-trans dicarboxylic acid wasobtained.

A-mi'x'ture of 20.6 g. oi2-(de1t'a carbo'Xy-butyl)thiophane-3,4-transdicarboxylic acid, 125 cc. of methanol, 175 cc. ofchloroformand 500. of concentrated sulfuric acid was refluxed forsixteen hours under a Soxhlet-apparatus containing anhydrous magnesiumsulfate in the thimble. The

solution was washed with several volumes of centrated to "about one halfits volume, diluted with-100 cc. of water 2.1101300 cc. of saturatedthirty minutes.

sodium bicarbonate solution and extracted with benzene. The benzeneextract on evaporation gave a small amount of unchanged triester. Thealkaline solution was acidified and extracted with benzene. The extract,washed with dilute hydrochloric acid, was evaporated leaving 17.6 g.(69%) of 2- (deltacarbomethoxybutyl)-3-carbomethoxythiophane-4-carboxylic acid.

To 25 g. of 2-(delta-carbomethoxybutyl)-3- carbomethoxythiophanetrans-4-carboxylic acid and cc. of benzene was added 25 cc. of thionylchloride and the mixture refluxed for fifteen minutes. The excessthionyl chloride and benzene were removed in vacuo. The residue in 100cc. of

"benzene was treated with 50 cc. of aniline. After five minutes themixture was washed twice with dilute hydrochloric acid, once with dilutesodium bicarbonate and finally water. Evaporation gave a semi-solidwhich was recrystallized from methanol. A yield of 6.8 g. of2-(delta-carbomethoxybutyl) 3 carbornethoxy-trans-4-carbanilidothiophanewas obtained.

To a warm solution of '7 g. of the compound immediately above in 70 cc.of methanol was added 7 cc. of 10% sodium hydroxide solution. Aftersixteen hours at room temperature, the solution was concentrated on thesteam bath with an air stream to remove most of the methanol, thendiluted with water containing sodium bicarbonate. The unchanged diester(1.? g.) was removed by filtration and the filtrate acidified. The solidwas collected on a filter. A yield of 4.7 g. (69%) of2-(delta-carbomethoxybutyl)-4- carbanilidothiophane trans 3 carbox licacid was obtained.

A mixture of 7.0 g. of Z-(deIta-carbomethoxyb-utyl)-4-carbanilidothiophane trans-3-carboxylic acid, 18 cc. of thionylchloride and 25 cc. of dry ether containing 0.5% pyridine was shakenoccasionally for thirty minutes. The mixture was evaporated to drynessin vacuo and the residue, dissolved in 50 cc. of acetone was added to astirred, ice cooled solution of 5 g. of sodium azide in 50 cc. of waterover a period of five minutes. After being stirred for thirty minutes at0 C., the mixture was diluted to 250 cc. with ice water containing 15cc. of saturated sodium bicarbonate solution. The slightly gummy azidewas removed by filtration, washed with ice Water and dried at roomtemperature and 1 mm. The azide was refluxed with cc. of aceticanhydride and 3.5 g. of anhydrous sodium acetate for one hour,nitrogen'evolution being complete in a few minutes. After the additionof 105 cc. of 6 N hydrochloric acid, the solution was refluxed forthirty minutes to remove the l-acetyl and ester groups, The solution wasconcentrated in vacuo until the product began to separate, then dilutedto 250 cc. with ice water. The product, 3 phenyl 8 (delta-carboxybutyl)5,6,8,9-

'tetrahydrothieno [3,4,ecisl uracil, was collected 'cc. of dry ethercontaining 0.5% pyridine was shaken occasionally for fifteen minutes.The solution was evaporated in vacuo, and the residue dissolved in 5-cc.of acetone and stirred with'0.3 gpof sodium azide in '3 cont water at 0C., for The mixture was diluted with ice water to 50 ca, cc. ofsaturated sodium bicarbonate was added, and the azide extracted withreagent ethyl acetate. The extracts were dried with anhydrous magnesiumsulfate at 0 C.,

i then refluxed for thirty minutes and evaporated to dryness in vacuo,The residual oily isocyanate was refluxed with 3 cc. of acetic anhydrideand 150 mg. of sodium acetate for twenty minutes. After the addition of3 cc. of 6 N hydrochloric acid, the solution was refluxed thirty minutesto remove the methyl ester and l-acetyl groups, evaporated to dryness invacuo and diluted with water and ethyl acetate. The product was removedby filtration and washed with water and ethyl acetate. A yield of 80 mg.of 3-phenyl-8- (delta carboxybutyl) 5,6,8,9-tetrahydrothieno [3,4,e,cis]uracil was obtained.

Example 3 To a solution of 320mg. oftransi-carbanilidothiophane-3-carboxhydrazide in 4 cc. of 0.5 Nhydrochloric acid cooled in an ice bath was added 100 mg. of sodiumnitrite in 1 cc. of water over a period of five minutes. The gummy azidewas extracted with reagent ethyl acetate and the extracts dried withanhydrous magnesium sulfate at 0 C. The solution was refluxed for twentyminutes, then evaporated to dryness in vacuo. The residual isocyanatewas refluxed with 3 cc. of acetic anhydride and 150 mg. of sodiumacetate for twenty minutes, then diluted with water; yield, 230 mg.(66%) of white crystals, melting point 236239 C. of1-acetyl-3-phenyl-5,6,8,9- tetrahydrothieno [3,4,e,cisl uracil. Amixture with an authentic sample prepared by a different method gave nodepression in melting point.

I claim:

1. Chemical compounds having the general formula:

in which X is a member of the group consisting of hydrogen, aliphaticand aromatic radicals, and R is a. member of the group consisting ofhydrogen, alkyl, carboxy, carboxyalkyl, carbalkoxyalkyl and.carbaryloxyalkyl radicals.

2. Chemical compounds having the general formula:

in which R is a carboxyalkyl radical.

3. 3-phenyl-8; (delta-carboxybutyl) -5,6,8,9-tetrahydrothieno[3,4,e,cisl uracil.

4. 3-phenyl-8- (delta-carbomethoxybutyl) -5,6,- 8,9-tetrahydrothieno[3,4,e,cis] uracil.

5. 3-methyl-8- (delta-carboxybutyl) -5,6,8,9-tetrahydrothieno[3,4,e,cisl uracil.

6. A method of preparing compounds having the general formula:

o=c--N-X in which X is a member of the group consisting of hydrogen,aliphatic and aromatic radicals and R is a member of the groupconsisting of hydrogen, alkyl, carboxyalkyI and carbalkoxyalkyl radicalswhich comprises heating a carbamylthiophane isocyanate with a carboxylicacid anhydride and a mild alkali and subsequently with a mineral acid.

'7. A method of preparing compounds having the general formula:

in which R is a member of the group consisting of hydrogen andcarboxyalkyl radicals which comprises heating a compound having theformula:

in which R is a member of the group consisting of hydrogen andcarbalkoxyalkyl radicals, with a .carboxylic acid anhydride and a mildalkali and subsequently with a mineral acid.

8. A method of preparing a 3-pheny1-8-carboxyalkyl5,6,8,9-tetrahydr0thieno [3,4,e,cis] uracil which comprises heating a2-carbalkoxyalkyl- 4-carbanilidothiophane-3-isocyanate with an alkalimetal acetate and acetic anhydride and subsequently with a mineral acid.

9. A method of preparing 3-phenyl-8-(deltacarboxybutyl) -5,6,8,9tetrahydrothieno [3,4,e,cisl uracil which comprises heating2-(delta-carbomethoxybutyl) -4-carbanilidothiophane-3-isocyanate with analkali metal acetate and acetic anhydride and subsequently with amineral acid.

10. A method of preparing 3-methyl-8-(deltacarboxybutyl)-5,6,8,9-tetrahydrothieno [3,4,e,cis] uracil which comprises heatingZ-(deIta-carbomethoxybutyl) -4-methylcarbamylthiophane 3 isocyanate withan alkali metal acetate and acetic anhydride and subsequently with amineral acid.

BERNARD R. BAKER.

